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BENTON CITY -- Rachel Little is planning a party to restore salmon habitat in the lower Yakima River.
Little, salmon biologist and educator for the Benton Conservation District, has organized a water stargrass work party Saturday in Benton City to remove heavy mats of the fast-growing aquatic plant.
Water stargrass has choked much of the lower 43 miles of the Yakima below Prosser to the Columbia River, covering traditional spawning grounds for chinook salmon and forcing them farther upstream, Little said.
For landowners, especially those who draw irrigation water from the river, water stargrass is a nuisance that regularly plugs screens and intake pipes. It also has discouraged recreational use and is an eyesore for those who live along the river.
"The lower Yakima used to be the prime chinook spawning ground in the Yakima. But since 2000, water stargrass has exploded every year and salmon spawning has decreased," Little said.
"Now, there's no evidence of spawning below Prosser Dam. It's all moved back above Prosser."
The most effective way to eliminate water stargrass is to yank it out by its roots and remove it from the river. So Little is seeking volunteers to meet her at the Benton City boat launch at 9 a.m. Saturday to carpool to a work site.
Volunteers are asked to bring a personal flotation device if they have one, as well as drinking water and to wear old tennis shoes or water sandals. The river is waist to ankle-deep where the water stargrass is to be pulled, she said.
Pulling parties also are scheduled on Saturdays through August at the same location, which was identified by Paul Hoffarth, district fish biologist for the Washington Department of Fish and Wildlife, as a salmon spawning bed.
In 2003, Hoffarth said, 286 spawning nests, or "redds," were counted between Horn Rapids and Benton City, and about one-third of them were close to that location. But the number of spawning returns "really started dropping off after that year," he said.
"It'll be interesting to see the results after they remove (the water stargrass)," Hoffarth said. "Once upon a time we had good spawning habitat and fairly strong numbers for the size of the Yakima."
Now, however, chinook must travel farther upstream to spawn. And the resulting longer journey downstream in the spring is particularly hard on the young smolts because they are exposed to predators for a longer period, Hoffarth said.
Members of local conservation groups, including the Richland Rod & Gun Club, and others already have indicated their intent to help on upcoming Saturdays, Little said. The intent is to clear an area the size of a football field.
Volunteers will pull the water stargrass -- which forms heavy mats and spreads by runners similar to a strawberry plant -- roll it up and put it on a float built by local farmer Dale Harkins, Little said. Harkins plans to compost the dried plants.
Pulling stargrass by the roots has been effective in test plots in the river, said Little, who relied on state and federal grants to study potential removal solutions. The $30,000 project is funded by the National Fish & Wildlife Foundation.
"If we get these roots out now, it won't be able to (re-establish) itself over the winter," Little said. "If we can get the roots, there is a good chance it won't come back."
Larry Cadwell, a landowner along the river and a board member of the Benton Conservation District, would welcome a water stargrass-free river.
"It can get pretty bad. Most of the shallower areas of the river are choked with stargrass, and in July when the river gets shallower, the stargrass just takes off," he said. "There are places where it covers the river from shore to shore."
Cadwell, who grows cherries, and other growers on the river also must continually clear irrigation intake pipes and filters of stargrass.
"When I started irrigating 30 years ago, I could run it all summer without clearing the filters," Cadwell said. "Now, depending on the water flow, it's weekly."
The water stargrass explosion, ironically, was an unwanted consequence of improved water clarity in the river, Little said. As turbidity in the river from polluting sources was cleared, the sun could penetrate farther into the water and stimulate growth of the plants.
Once water stargrass is removed, though, fish appear to respond quickly. The weed mats also reduce oxygen levels in the water, so fish tend to avoid it, Little said.
Last weekend, Little estimated she saw 75 fish feeding in a small clearing in the river where stargrass recently was removed.
"They like the openings we're making in the water, and it just looks so much better," said Little, who is mapping out future project sites. "This is an easy way to make a difference for the river."
To RSVP or for more information, Little can be reached at rachel-little@conservewa.net or the district office at 736-6000.
-- Kevin McCullen; 582-1535; kmccullen@tricityherald.com
